Various prior art documents disclose a technique related to an electromagnetic clutch. For example, the patent literature 1 is one of such prior art documents. The electromagnetic clutch of the patent literature 1 includes: a rotor that is rotated upon receiving a rotational force from a rotational drive source; a hub that is joined to a rotatable shaft of a compressor; a coil housing that receives and fixes a coil spool, around which an electromagnetic coil is wound; and an armature that is attracted to and attached to a friction surface of the rotor by an electromagnetic attractive force generated from the electromagnetic coil. A tilt surface is formed at an inner peripheral corner of the coil spool, which is located on the side where the friction surface of the rotor is placed. A thermal fuse is placed in a recess formed by the tilt surface. The thermal fuse is fused at or higher than a predetermined temperature to stop supply of an electric power to the electromagnetic coil.
However, in the electromagnetic clutch of the patent literature 1, due to the provision of the recess at the inner peripheral corner of the coil spool, a wire space, at which the electromagnetic coil is wound at the inner peripheral corner of the coil spool, is reduced in the axial direction of the electromagnetic clutch. Therefore, the size of the electromagnetic coil is reduced due to the provision of the thermal fuse. However, the inventors of the present application have found that there is a possibility of increasing the winding space in comparison to the electromagnetic clutch of the patent literature 1 through reconsideration of the arrangement of the thermal fuse. Specifically, the electromagnetic clutch of the patent literature 1 is not good enough in view of an objective of limiting a reduction of the winding space of the electromagnetic coil caused by the installation of the thermal fuse.